Airlays are used for opening fiber and putting the fiber into an air stream. A conventional airlay is disclosed in U.S. Pat. No. 3,797,074 to Zafiroglu issued on Mar. 19, 1974. However, one of the drawbacks or limitations of Zafiroglu is that it has difficulty opening medium and long staple fibers.
By comparison, carding machines are quite good at separating fibers into their individual filaments. However, the individualized fibers on carding machines are typically doffed at slow speeds into a carded web or sliver. To the extent that there are known techniques and arrangements for doffing the fiber from a carding machine into an air stream, such techniques are generally quite unsatisfactory. There are numbers of references, such as U.S. Pat. No. 3,641,628 to Fehrer, U.S. Pat. No. 4,097,965 to Gotchel et al., U.S. Pat. No. 4,130,915 to Gotchel et al., and U.S. Pat. No. 4,475,271 to Lovgren et al. which show air doffing cards. Typical of such arrangements is an air knife or air jets arranged to blow fiber from the doffing roll or main carding roll. With such arrangements, the fiber is carried away by a very turbulent air flow. Such highly turbulent air carries away the fibers in clumps and not individualized.
It has long been understood that carding offers certain advantages and airlays offers others. While it may appear logical to the unskilled person to simply feed a carded web to an airlay, there are significant technical and economic reasons that lead away from such an arrangement.
Carding machines and airlaying equipment are each quite expensive capital items and are generally considered by those skilled in the art to be mutually exclusive and separate technologies. Thus, one selects to use one technology or the other. The potential added value to the customer (the highest price the customer would be willing to pay for such products) would simply not justify the substantial added processing and equipment costs.
In addition to the economic drawbacks of feeding a carded web to an airlay, there are significant technical problems to overcome. Airlays are notorious for pulling clumps of fiber and dispersing the whole clump into the air stream. While the Zafiroglu technique has been used quite satisfactorily, it took significant subsequent development including the development by Contractor et al. in U.S. Pat. No. 3,932,915 on Jan. 20, 1976 to really get the system working satisfactorily. But even now, the fibers that are fed to the airlay are shorter than average staple length fiber.
Longer fibers are much more difficult to control coming through feed rollers or other feed mechanisms to be picked by the disperser roll. Most of the fiber opening done by an airlay is done by the interaction of the disperser roll and the feed rolls. Once the fiber is on the disperser roll, unless it is a chip of fibers, it is dispersed into the air stream in the same basic form in which it is carried to the duct. Pulling or picking a long fiber (as compared to a shorter fiber) from between the feed rolls more typically causes other long fibers to be pulled through the feed rolls with it. With each such long fiber, the disperser picks a clump of fibers. However, if the feed rolls are arranged to press tighter together to control clumping, the fibers may be stretched and broken or the fibers may drag hard through the feed rolls causing the build up of frictional heat. Either result will be deleterious to the commercial operation of the airlay. The problems are particularly exacerbated by the nature of carding machines which tend to provide linearly oriented fibers. As such, the fibers enter the feed rolls in the worst possible orientation for the disperser roll to pick them from the feed rolls. The arrangement for feeding carded fiber to an airlay would be one of the first problems to be overcome to achieve successful operation.
In spite of the apparent difficulties, it is an object of the present invention to provide a system and process for centrifugally dispersing individualized carded fiber which overcomes the above noted drawbacks of the prior art.
It is a more particular object of the present invention to provide a system and process for taking fiber from a carding machine and feeding it to an airlay which overcomes or avoids the problems described above.